A nozzle arrangement for a paint spray gun is described in German Utility Model G 90 01 265.8. The nozzle arrangement described in that document has a central outlet for the paint which can be closed with an axially extending pin. The paint flows pressureless from a fluid container to this sealable outlet. The outlet is surrounded by an annular slot out of which a circular air jet of high velocity flows, which thereby sucks paint out of the outlet, atomizes it and carries it along, as a result of which a circular jet consisting of paint particles is formed.
Laterally of the jet direction, the nozzle arrangement has two protruding horns, horn air jets of which are directed diagonally and in the same direction to the direction of flow of and into the circular jet, which deforms it. To control the horn air, the nozzle arrangement has, on both sides of the outlet in the direction of the horns, two or more control bores through which air passes and impacts the horn air jets and thus controls them.
Both the annular slot and the control bores are supplied with air from the same air chamber, namely an annular duct inside the nozzle arrangement. This annular duct is supplied with compressed air from supply bores which are located in a paint nozzle and the axes of which are arranged parallel and equidistant on a circle around the axis of the nozzle arrangement.
A disadvantage of the arrangement described is that the air does not flow uniformly into the annular slot via the supply bores arranged about the periphery inside the nozzle arrangement, as a result of which the air/paint mixture is not distributed as uniformly as possible in the circular jet. If the air pressure were measured along the periphery of the annular slot, then an almost sinusoidal modulation would result, whereby peaks occur in the angular area of the annular slot, in which the bores are also located, and minimums in between.
In addition, this arrangement has the disadvantage that the air from the supply bores reaches directly into the control bores for the horn air, depending on the angular position of the paint nozzle having the bores relative to the housing or air cap of the paint spray gun, when the supply bores are about colinear with these control bores and, as a result, the horn air is affected too greatly in an undesirable manner, which in turn changes the jet pattern in an undesirable manner. The spray result thus depends on the relative position of the air cap having the horns and control bores relative to the paint nozzle which has the supply bores. However, the position of the paint nozzle screwed into the housing of the paint spray gun is determined by the starting cut of its thread and thus a great extent accidental, so that some of the guns produced exhibit undesirable paint coat properties.